Burning-in machine



SePf- 8, 1953 w. FlBURKE Erm. 2,651,702

. BURNING-INl MACHINE Filed Dec. 13. 1949 5 Sheets-Snetl G i MUM A m l o k) IN VEN TORJ wuz/AM Aam/fi om' f. .awww/y BY fm@ www@v Sept. 8, 1953 w. F. BURKE ETAL BURNING-INy MACHINE 5 sheets-sheet Filed Dec. 13, 1949 Sept. 8, 1953 w. F. BURKE ETAL 2,651,702

BURNING-IN MACHINE Filed Dec. 13. 1949 3 Sheets-Smet 3 Patented Sept. 8, 1953 BURNING-IN MACHINE William F. Burke and Otis F. Simpson,

Athens,

Ohio, assignors to The McBee Company, Athens, Ghio, a corporation Application December 13, 1949, Serial No. 132,672

(Cl. Z119- 19) '7 Claims.

This invention relates in general to the art of photoengraving, and more particularly to a device for burning in or fusing etching powder to engraved plates.

Photoengraving is a method for the production of metallic printing surfaces in relief, usuu ally for illustrating purposes, from drawings, photographs, objects or textual matter, with the ultimate object of multiplying copies thereof by the printing press. The process is characterized by the following steps: An ima-ge cf the subject is irst obtained by means of the camera, as a negative or positive, and is then transferred by photographic exposure directly onto the metal plate prepared with light-sensitive coating, thus creating a hardened image which allows the unprotected parts to be etched by chemical or electrolytical action below the printing surface. To maintain proper definition of the raised or printing areas, undercutting of these areas during the etching process must be avoided. To this end the etching process is eifected in several stages and after each stage or so-called bitej except the last stage, a protective coating of powder is applied to the upstanding walls of the printing areas. More specically, after each such bite other than the last bite, the plate is brushed with a powder in one direction so that a bank is piled against one side of each of the slightly elevated printing areas. The plate is then heated to fuse this powder to these edges, 'then cooled so that the process, usually referred to as burning in can be applied successively to the other three remaining sides or edges of each of the raised printing areas.

It is important to use the proper degree of heat during each burning in stage for if insufiicient heat is applied the powder may chip, and if overheating occurs the powder will shrink and char,

thereby decreasing the adhesion between the e fused powder and the plate which in turn may also cause chipping.

Currently, the burning in process is effected 'manually over a gas burner, a procedure which is objectionable for several reasons. place there is a lack of uniformity in treated plates for the temperature to which the plate raised and maintained depends upon the experience and judgment of the operator. The very fact that the operator is flame makes the operation more difficult and the results uncertain. In the second place the heat transfer required to raise the temperature of the plate to the point at which the powder will fuse with it proceeds largely by conduction in the nrst i working over a hot through the plate to the powder, a relatively slow process, frequently resulting in overheating the powder through overheating the plate.

In general the object of this invention is the provision of an automatically operating and controlled machine for eifecting the burning in process above referred to.

Another object of the invention is the provision of a burning in oven having heating units designed to primarily radiate infrared rays.

Still another object of the invention is the provision of a burning in oven to which plates can be delivered byv a carriage to thus avoid the necessity of having an operator work in the immediate vicinity of the oven.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description where that form of the invention which has been selected for illustration in the drawings accompanying and` forming a part of the present specification is outlined in full.

in said drawings, one form of the invention is shown, but it is to be understood that it is not limited to such form, since the invention as set forth in the claims may be embodied in a plurality of forms.

eferring to the drawings:

Fig. 1 is a side elevation of a burning in oven embodying the objects of our invention;

Fig. 2 is a left-hand end view of the oven shown in Fig. 1;

Fig. 3 is a section taken on a line 3-3 of Fig. 1;

Fig. 4 is a schematic electrical diagram of the electrical circuit and equipment associated with and forming a part of the oven illustrated in the above figures.

General description As shown in these drawings, the objects of our invention have been embodied in a machine comprising a frame generally designated by the reference numeral l; an infrared oven mounted on one end of the frame and generally designated by the reference numeral 2; a plate carrier generally designated by the reference numeral 3 and arranged to travel longitudinally on the frame into and out of the oven; and an electrical circuit generally designated by the reference numeral d for controlling the operation of the oven and for locking the plate carrier beneath the oven.

Frame More specifically the frame includes 3 pairs of vertical legs 5, 6 and l; horizontal side braces 8,

' ably aesioa sa Si and i i; front and rear horizontal end braces i2; and intermediate transverse braces it, it and i5.

Oven mounting Mounted over the right-hand end of the 'frame i as Viewed in Fig. l is the oven 2, the oven being adjustably suspended from a transverse crossbar iiimounted on opposed pairs of upstanding bars il, these bars in turn being supported by opposed angle plates iii and held in spaced relation by spacing blocks it. The bars il are bolted to the plates by angles 2i and the plates ld are bolted to upstanding legs t and '5. To increase the rigidity of this structure diagonal braces 22 are .isposed between the upper ends of the upstanding bars il and the angles 2i.

Bolted to the crossbar i intermediate its ends is a plate 23 and threaded through this plate and extending through a hole formed in the bar i is a screw 2d. rThe lower end of the screw is rotatsecured to a transverse heater supporting bar 25 by a plate 25 bolted to the bar 25, the ends of the bar extending between the upstanding bars il. The bars il therefore constitute guiden ways for the bar i5. Keyed to the screw 2d intermediate its ends in a hand wheel 2i for adjusting the vertical position of the bar 25. Mounted on the crossbar iii adjacent the upper free end of the screw 213 is an upstanding linear scale 28 and adjustably fastened to the screw opposite this scale is a collar 29 provided with an outwardly extending flange 3i serving as a circular pointer. Fastened between the outer ends of the bars i6 and 2d are coil springs 32 serving to bias the bar 25 and its load upwardly. Rig-'idly bolted to the outer ends of the bar 25 are guide rails 33 arranged to slide against one of each of the pairs of the upstanding bars il. The upper ends of the guide rails 33 slide through guide clips and as a result of this construction the heater supporting bar 25 is maintained a horizontal position.

Oven

The oven i includes three parallel downwardly directed reflectors 35, 36 and .i'i, the two outer reflectors being supported from straps and til through links ii secured to the end plates of the reflectors. The straps it' and 39 are in turn fastened intermediate their ends to the sup porting bar 25. Fastened to the ends of the bar and extending downwardly therefrom are blocks i2 and secured thereto are the links il of the intermediate reflector 2id. Forming extesions of the reflector end plates are skirts li. Disposed and secured within each of the reflectors Sii and t'i are tubular heating elements 15 and iii of the infrared type.

Plaie carrier Mounted on the opposed, parallel and longitudinally extending side braces 8 are a pair of rails i'i each provided with grooved tracks lit. Movable over the tracks 135i is the plate carrier this carrier being of inverted box form and provided with rollers de receivable in the grooved tracks dii. As indicated in Fig. l, the rails ii extend throughout the length of the machine to thereby permit the carrier to be moved into and out of registration with the oven 2.

Fastened to each side of the frame i at its left-hand end as viewed in Fig. l, is a forwardly inclined angle plate 5i and supported thereon are rollers 52 carried on the ends of a cross shaft 53. Mounted on the shaft 53 intermediate its ends are counterweights 515 and secured to the shaft by rings 55 are a pair of cables 5t. The cables 56 pass over sheaves 51 mounted on the front brace i2 and are then fastened to the rear end of the plate carrier 3. As a result of this expedient the plate carrier is always biased towards the front end of the machine.

To cushion the forward terminal movement of the carrier a bumper generally designated by the reference numeral 58 is mounted on the front brace l2. The bumper 58 includes a block 5d formed with a recess 6l for the reception of a biasing coil spring 62. Extending through the block 59 and through the spring 62 is a pin having an enlarged rear end arranged to be engaged by the forward end of the carrier 3 upon the forward terminal movement of the carrier.

Pivoted to an ear Eel extending upwardly from the transverse brace I5 is a lever t5 having a shoulder t5 engageable with a spring-loaded latch @5a. pivoted to the forward end of the cai rier El when the carrier, as shown in Fig. l in dot-dash line, is made to assume its operative position beneath the oven 2 so as to hold the carrier in this position under the control of the electrical circuit il presently to be described.

Electrical circuit The electrical circuit shown in Fig. 4 and generally designated by the reference numeral l includes a primary circuit generally designated by the reference numeral 1I for energizing the heating units dit, d5 and 46 and a control circuit generally designated by the reference numeral 'i2 for manually controlling the primary circuit during the oven preheating operation and for automatically controlling the primary circuit during the actual burning in operation.

rEhe primary circuit includes a pair of leads it and lll arranged to communicate through a switch l5 with a source l5 of 220 volt alternating current. Connected in parallel with the leads ifi and 'ifi through individual rheostats '11, it and are the heating units lid, 45 and is respectively, these units as above stated being designed predominantly to emit infrared rays. Connected in series with the leads 13 and 14 is the coil Si of a solenoid S2, the plunger S3 of the solenoid being linked to the free end of the lever. Upon the closing of the switch T5, the coil 8i is energized as well as the heating units 44, 45 and lid. Upon the energization of the coil 8l, the plunger 83 is drawn downwardly thereby elevating the left end of the lever 55 into its locking position against the action of a biasing spring 34 disposed be tween the lever and a portion of the frame i.

The switch 'i5 is linked to and under the control of a plunger 35 of a solenoid 86 having a coil 3l in circuit with the control circuit '52. More specifically the coil Bl communicates through leads 83 and 89, a manually operated switch di and a lead 92, with leads S3 and S4, which in turn communicate with a source of 110 volt altern nating current. Shunted across the leads 53 and Sil through a lead 95, one leg of the switch di and the lead 92 is a tell-tale lamp 9i. lt will therefore be seen that closing of the manual .switch Si serves to energize the lamp Si and the solenoid coil 8l, the latter in turn serving to close the switch 'i5 of the primary circuit.

In addition to this the control circuit includes a switch Els under the control of a timer switch sil. One terminal of the timer switch S9 communicates through a lead IUI with one of the terminals of the switch 98, and through one leg of this switch and a lead 102 with the leads 92 and 93.

The other terminal of the timer switch communi- Cates through a lead |03 with one terminal of a conventional microswitch |04 provided with a biasing spring for normally holding it in its open position. The switch |04 is closed in response to the movement of anger H pivote-d to the frame i in the path of the plate carrier 3 and which therefore moves rearwardly upon the rearward terminal movement of thev carrier to its operative position beneath the oven 2. The remaining terminal of the microswitch HillV communicates through a lead |56 with the lead 88. One terminal of the switch 98 commu-nicates through a lead i8? with the lead 89 and through this lead with the solenoid coil 81.

ln the operation of this latter circuit the timer switch 99 is first set to remain closed for any selected time interval and is then closed. The closing of this switch serves simultaneously to close the switch G8 and to hold it closed so long as the timer switch remains closed. Upon the closing of the switch Si! the solenoid coil 8'! is energized with the consequent completing of the primary circuit. Simultaneously the solenoid coil Si is energized and the lever t5 brought into its latching position. The microswitch Hit is closed under the induence of the rearward terminal movement of the plate carrier 3, thereby energizing the timer of the timer switch 98. Upon the elapse of the time interval for which the timer of the timer switch has been set to operate, the timer operates to open the switch 93 whereupon the lever 55 is permitted to drop to its unlatched position.

An indication of the temperature within the oven 2 can be obtained by mounting a thermopile t on the inner face of one of the oven shirts 43 and connecting the thermopile with a millivoltmeter m mounted on the frame i adjacent the timer switch. Preferably the millivo-ltrneter is calibrated in degrees and therefore serves as a pyrometer.

Operation of the machine rPhe heat transferred from the oven to a plate supported beneath it on the carrier depends on three factors: the distance between these two elements, the current passing through the heating units, and the interval of time during which the transfer of heat is taking place. The distance between the carrier and the plate is conveniently .isted by the handwheel 27, the pointer 3| 7ing an indication of this factor. To vary the rrent passing through each of the heating units ecert is had to the rheostats 1T, 18 and '19 conveniently mounted on a suitable panel Hi8 iastened to the oven unit 2 adjacent the timer switch t9 which is also carried by the oven unit 2 together with the switches 15, 9| and 98, the solenoid ES and the lamp S7. As already indicated the timer of the timer switch 99 controls the time element. The proper values for these three variables can of course be ascertained by test runs and if desired can be adjusted during actual operation.

Preliminary to burning in a powdered plate, the oven 2, the carrier 3 and its associated plate rack r should be brought up to the operating temperoture, being essential for the purpose of eliminating variations in the initial temperature of the device and bringing about a more certain temperature control and heat transfer. In this connection it is to be noted that the transfer of heat from one body to another depends upon the emperature differential between the two bodies.

This so-called preheating of the device is effected by closing the manual switch 9| which as above stated serves to close the switch l5, energize the heating units 44, 45 and 46, energize the solenoid coil 8| and elevate the left end of the lever t5 to its latching position. Following this the plate carrier 3 is retracted against the` action of the biasing weights 5d, to its rearward terminal position beneath the oven 2. The lever operates to hold the carrier in this position until the switch Si is opened at such time as the pyrorneter above referred to indicates that the device has been preheated to its operating ternperature.

In the meantime a partially etched plate p is powdered and brushed in accordance with standard practice preparatory to being burned in. This having been done the manual switch 9| is opened, whereupon the solenoid coil 3i is deenergized thereby permitting the left-hand end ci the lever 555 to drop under the influence of the spring i3d, which in turn permits the plate carrier and its plate rack 1' to move to its forward terminal and loading position under the influence of the biasing weights 54.

The powdered and brushed plate p is then deposited on the rack r which is merely a rectangular openworifr grid for spacing the plate p from the carrier to permit the circulation of hot air around the plate and partially to insulate the carrier against conducted heat. The timer switch 53 is then closed and the carrier 3 moved to its operating position beneath the oven, whereupon the micro-switch lfl closes to complete the timer switch circuit. The timer switch circuit and ccnsequently the primary circuit remains closed until the pre-selected time interval has elapsed, whereupon the timer operates to open to switch Q8. As a result of this the heating units 4d, d5 and are cie-energized and the carrier 3 released and moved forwardly to its unloading and loading position. To signal the return or" the carrier to this position a bell b is mounted on the frame in circuit with and under the control ci switch s mounted on the frame in the path of the carrier and so arranged that it functions to close this circuit selectively only in response to the forward movement of the carrier.

From the above description it will be appreciated that we have provided a machine for burning in powdered plates whereby the various iactors controlling the transfer of heat are under close control, whereby the timing factor is automatically controlled, and whereby the operator is relieved of the necessity of working in close proximity to the heating elements. Furthermore, the use of heating elements designed primariy to radiate infrared rays results in a more rapid heating of the plates without overheating and chipping of the protective powder banks.

We claim:

l. A machine comprising: a frame; a horizontal track supported by said frame; a heating element adjustably mounted on said frame over one end of said track; means mounted on said frame for adjusting the vertical position of said heating element relative to said track; a carriage mounted on said track for movement thereon into and out of vertical registration with said heating element; means urging said carriage out of vertical registration with said heating element; an electrical circuit connected to said heating element for energizing said heating element; a latch mounted on said frame in the path of said carriage for holding said carriage 7 in its operative position in vertical registration with said heating element; and means for activating said latch in response to the iiow of current through said electrical circuit.

2. A machine comprising: a frame; a horizontal track supported by said frame, one end of said track constituting a treating zone and its other end a loading Zone; a heating element mounted on said frame over said track in the treating zone thereof; means for adjusting the vertical position of said heating element relative to said track; a carriage mounted on said track for movement thereover between said treating and loading zones; a latch mounted on said frame in the path of said carriage for holding said carriage in said treating zone; a rst solenoid mounted on said frame, the plunger of said solenoid being linked to said latch and operative upon the energization of the coil of said solenoid to hold said latch in latching position; a primaryl electrical circuit connected to said heating element and said rst solenoid for energizing said heating element and said first solenoid; a nrst switch attached to said primary circuit for making and breaking said primary circuit; and a` control circuit having a manually operated switch, an independently operable timer switch and a second solenoid, said control circuit being under the independent control of the manually operated switch and the timer switch, and upon energization or" said control circuit said second solenoid actuates said first switch or" the primary circuit.

3. A machine comprising a frame, a horizontal track supported by said frame, an electrical heating unit mounted on the frame above a portion of the track, a carriage on said track movable to an operable position in registration with said heating unit and to an inoperative position out of registration with said heating unit, means for latching the carriage in its operative position, electric circuit means including a timer and a control solenoid for the latch for supplying current to the heating means for a predetermined period of time and then to terminate the supply of current to the heating unit and to the solenoid to cause unlatching of the latching means, and a mechanical arrangement for moving the carriage to its inoperative position when the carriage is unlatched.

4. A machine comprising a frame, a horizontal track supported by said frame, an electrical heating unit adjustably mounted on said frame over one end of said track, means mounted on said frame for adjusting the vertical position or" said heating unit relative to said track, a carriage mounted on said track for movement thereon into and out of vertical registration with said heating unit, means for moving said carriage out of ver tical registration with said heating unit, a primary electrical circuit connected to said heating unit and having a solenoid, said solenoid upon energization operable to move a latch mounted on said frame in the path of said carriage to a position for holding said carriage in its operative position in vertical registration with said heating element, and a control circuit having a timer switch and a solenoid, said timer switch upon energization operable to hold said circuit closed for a predetermined period of time and thereafter to open said circuit, said solenoid operable upon energization to close the primary circuit and upon cle-energization to open said primary circuit.

5. A machine comprising a trame, a horizontal track supported by said frame, an electrical heating unit mounted on the frame above a portion of the track, a carriage on said track movable to anoperable position in registration with said heating unit and to an inoperative position out `of registration with said heating unit, means for latching the carriage in its operative position, a primary electrical circuit including said heating unit, an electrically operated switch and a soleinoid for activating said latching means upon the closing of said electrically operated switch, a control circuit including a timer switch, a microswitch and a solenoid, said timer switch movable to a closed position and operable to remain in a :closed position for a set period of time upon the energization of the circuit, said microsvvitch constantly urged to an open position and operable to be moved to a closed position by said carriage when said carriage is moved to an operable po- :sition in registration with said heating unit and thereby energizing said control circuit, said solenoid operable upon the energization of the control circuit to close the switch oi the primary circuit, and a mechanical arrangement for automatically moving the carriage to its inoperative position when the timer switch opens the circuit .and the carriage is unlatched.

G. A machine comprising a frame, a horizontal track supported by said frame, one end of said 'track constituting a treating zone and its other end a loading zone, an electrical heating element mounted on said frame over said track in treating zone thereof, means for adjusting the vertical position of said heating element relative to said track, a carriage mounted on said track for movement thereover between said treating and loading zones, means constantly urging s carriage toward the loading zone, a latch mounted on said frame in the path or said carriage for holding said carriage at said treating zone, a first solenoid mounted on said frame, the plunger of said solenoid being linked to said latch and operative upon the energization of the coil or said solenoid to move said latch to a lat/ching position and to hold it in such a position; a primary electrical circuit ior energizing said heating element, said primary circuit including said rst solenoid and a switch for making and breaking the circuit, and a control circuit including a timer switch, a microswitch, and a second. solenoid, said timer switch being movable to a closed position and upon the energizing ci the circuit to hold said switch in the closed position for a set period of time, said microswitch adapte to be closed by said carriage when the carriage is in the treating zone and thereby energize said control circuit, said second solenoid operable upon the energization of the control circuit to close the switch oi the primary circuit, thereby energizing said heating elements and said nrst solenoid.

7. A machine comprising a frame, a horizontal track supported by said frame, an electr'cal heating element adjustably mounted on said frame over one end of said track, means mounted on said frame for adjusting the vertical position of said heating element relative to said track, a carriage mounted on said track for movement thereon into and out of vertical regist"ation said heating element, a latch moi/ably said frame in the path of said carriag latch movable to a position for holding said carriage in its operative position in vertical registration with said heating element, a primary ele"- trical circuit including said heating element, a

solenoid, and a switch, said solenoid operable upon energization to move said latch to its holding position, a secondary circuit having a timer switch, a microswitch, and a solenoid, said timer switch operable to be moved to a closed position and to hold said closed position for a predetermined period of time after the secondary circuit is energized, said microswitch operable to be closed by said carriage when said carriage is moved to its position of vertical registration with said heating element, whereby said secondary circuit is closed and is thus energized, and upon the energization of said circuit said solenoid is energized and is operable to move the switch of the primary circuit to a closed position and thus energize the primary circuit, and upon the lapse of the predetermined period of time said timer switch moves to its open position and deenergizes the control circuit and the deenergized solenoid in the control circuit is moved to a position whereby the switch of the primary circuit is moved to an opened position and the solenoid in the primary circuit is de-energized and said latch moves to a non-holding position l0 and said carriage is free to move out of vertical registration, and mechanical means for automatically moving said carriage when released out of vertical registration with said heating element, whereby said microswitch is moved to its open position.

WILLIAM F. BURKE. OTIS F. SIMPSON.

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